ISO 14222:2022

INTERNATIONAL ISO
STANDARD 14222
Second edition
2022-03
Space environment (natural and
artificial) — Earth's atmosphere from
ground level upward
Environnement spatial (naturel et artificiel) — Haute atmosphère
terrestre
Reference number
ISO 14222:2022(E)
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© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
ISO 14222:2022(E)
Contents  Page
Foreword .iv
Introduction .v
1 Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
4  Symbols and abbreviated terms.6
5  General concept and assumptions .7
5.1 Earth's atmosphere model use . 7
5.1.1 General . 7
5.1.2 Application guidance . 7
5.2 Earth wind model use . 8
5.3 Robustness of standard . 8
5.4 Long-term changes of the atmosphere . 8
Annex A (informative) Neutral atmospheres .10
Annex B (informative) Natural electromagnetic radiation and indices .32
Bibliography .47
iii
ISO 14222:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 14222:2013), which has been technically
revised.
The main changes are as follows:
— updated formulae, references to models, indices and links to websites;
— this document now applies to the Earth's atmosphere from ground level upward through the
exosphere.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO 14222:2022(E)
Introduction
This document provides guidance for determining the properties of the Earth’s atmosphere from
ground level upward to the exosphere.
In the atmospheric regions up to approximately 100 km, a detailed knowledge of the average structure
of the atmosphere as a function of geographic location, time in the year and solar activity is critical
for the design of aircraft, balloon payloads, rocket launch activities and many other facets of modern
society. The maximum departures from average conditions also need to be understood in order to
provide a margin of safety in design and in operations. These features are included in this document.
A good knowledge of temperature, total density, concentrations of gas constituents, and pressure in
the region above about 100 km is important for many space missions exploiting the low-earth orbit
(LEO) regime below approximately 2 500 km altitude. In addition to the causes of variation of the
atmosphere up to 100 km, geomagnetic processes may seriously affect the structure and dynamics
of the thermosphere. Aerodynamic forces on the spacecraft, due to the orbital motion of a satellite
through a rarefied gas which itself can have variable high velocity winds, are important for planning
satellite lifetime, maintenance of orbits, collision avoidance manoeuvring and debris monitoring,
sizing the necessary propulsion system, design of attitude control system, and estimating the peak
accelerations and torques imposed on sensitive payloads. Surface corrosion effects due to the impact
of large fluxes of atomic oxygen are assessed to predict the degradation of a wide range of sensitive
coatings of spacecraft and instruments. The reactions of atomic oxygen around a spacecraft can also
lead to intense “vehicle glow”.
The structure of Earth’s atmosphere and internationally accepted empirical models that specify the
details of the atmosphere are included in this document. The annexes and references provide a detailed
description the details of those models. The purpose is to create a standard method for specifying
Earth's atmosphere properties (density, temperature, wind etc.) at all altitudes from ground level
upward, including the low Earth orbit regime now widely-used for space systems and space operations.
The details of those models are included in Annex A.
Annex B provides a detailed description of the electromagnetic radiation and solar and geomagnetic
indices.
v
INTERNATIONAL STANDARD ISO 14222:2022(E)
Space environment (natural and artificial) — Earth's
atmosphere from ground level upward
1 Scope
This document specifies the structure and properties of the Earth’s atmosphere from ground
level upward. It provides internationally accepted empirical models that specify the details of the
atmosphere. It also refers to widely-accepted physical models providing insight into the physical and
chemical processes driving the response of the atmosphere.
2  Normative references
There are no normative references in this document.
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
homosphere
region of the atmosphere that is well mixed
Note 1 to entry: The major species proportional concentrations are independent of height and location.
Note 2 to entry: This region extends from 0 km to ~100 km and includes the temperature-defined regions of the
troposphere (3.2) (surface up to ~6 km to 18 km altitude), the stratosphere (3.3) (~6 km to 18 km up to 50 km
altitude), the mesosphere (3.4) (~50 km up to about 90 km altitude), and the lowest part of the thermosphere (3.5)
(~90 km to 125 km).
3.2
troposphere
lowest layer of the Earth’s atmosphere
Note 1 to entry: It is also where nearly all weather conditions occur.
Note 2 to entry: The troposphere contains approximately 75 % of the atmosphere’s mass and 99 % of the total
mass of water vapour and aerosols. The average height of the tropopause is 18 km (11 mi; 59 000 ft) in the tropics,
17 km (11 mi; 56 000 ft) in the middle latitudes, and 6 km (3.7 mi; 20 000 ft) in the polar regions in winter. The
global average height of the tropopause is 13 km.
Note 3 to entry: The lowest part of the troposphere, where friction with the Earth's surface influences air flow,
is called the planetary boundary layer. The boundary layer is typically a few hundred metres to 4 km deep
depending on the landform, latitude, season and time of day. The upper boundary of the troposphere is the
tropopause, which is the border between the troposphere and stratosphere (3.3). The tropopause is an inversion
layer, where the air temperature ceases to decrease with height and remains constant through its thickness.
ISO 14222:2022(E)
3.3
stratosphere
second major layer of Earth’s atmosphere, immediately above the troposphere (3.2) and below the
mesosphere (3.4)
Note 1 to entry: The stratosphere is stratified (layered) in temperature, with warmer layers higher and cooler
layers closer to the Earth; this increase of temperature with altitude is a result of the absorption of the Sun's
ultraviolet radiation by the ozone layer. This is in contrast to the troposphere (3.2), near the Earth's surface,
where temperature decreases with altitude. The border between the troposphere (3.2) and stratosphere, the
tropopause, marks where this temperature inversion begins. Near the equator, the stratosphere starts at as high
as 18 km, around 17 km at midlatitudes, and at about 6 km at the poles. Temperatures range from an average
of −51 °C near the tropopause to an average of −15 °C near the stratopause [the boundary with the mesosphere
(3.4)]. Stratospheric temperatures also vary within the stratosphere as the seasons change, reaching particularly
low temperatures in the polar night (winter). Winds in the stratosphere can far exceed those in the troposphere
(3.2), reaching near 60 m/s in the Southern polar vortex.
3.4
mesosphere
layer of the Earth’s atmosphere that is directly above the stratosphere (3.3) and directly below the
thermosphere (3.5)
Note 1 to entry: In the mesosphere, temperature decreases as the altitude increases. This characteristic is used
to define its limits: it begins at the top of the stratosphere (3.3) (sometimes called the stratopause), and ends at
the mesopause, which is the coldest part of Earth's atmosphere with temperatures frequently below −143 °C. The
exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at
the tropics, lower in summer and at the poles), but the lower boundary is usually located at heights from 50 km to
65 km above the Earth's surface and the upper boundary (mesopause) is usually around 85 km to 100 km.
Note 2 to entry: The stratosphere (3.3) and the mesosphere are collectively referred to as the “middle atmosphere”,
which spans heights from approximately 10 km to 100 km. The mesopause, at an altitude of 80 km to 90 km,
separates the mesosphere from the thermosphere (3.5) – the second-outermost layer of the Earth's atmosphere.
This is also approximately the same altitude as the turbopause. Below the turbopause, different chemical species
are well mixed due to turbulent eddies. Above this level the atmosphere becomes non-uniform; also, above the
turbopause, the scale heights of different chemical species differ by their molecular masses.
3.5
thermosphere
region of the atmosphere between the temperature minimum at the mesopause (~90 km) and the
altitude where the vertical scale height is approximately equal to the mean free path (400 km to 600 km
altitude, depending on solar and geomagnetic activity levels)
Note 1 to entry: At its lower boundary with the mesosphere (3.4), the composition is close to that found at ground
level. In the upper thermosphere, the composition is usually mainly atomic oxygen.
3.6
exosphere
region of the atmosphere that extends from the top of the thermosphere (3.5) outward
3.7
NRLMSIS 2.0
Naval Research Laboratory mass spectrometer, incoherent scatter radar extended model
model that describes the neutral temperature and species densities in Earth's atmosphere from ground
level upward, including the troposphere (3.2), stratosphere (3.3), mesosphere (3.4), thermosphere (3.5)
and exosphere (3.6)
Note 1 to entry: It is based on a very large underlying set of supporting data from satellites, rockets, and radars,
with extensive temporal and spatial distribution. It has been extensively tested against experimental data by the
international scientific community. The model has a flexible mathematical formulation.
Note 2 to entry: It is valid for use from ground level to the exosphere (3.6). Two indices are used in this model:
F (both the daily solar flux value of the previous day and the 81-day average centred on the input day) and A
10,7 p
(geomagnetic daily value)
ISO 14222:2022(E)
Note 3 to entry: See References [1] and [2].
3.8
Earth GRAM 2016
Earth GLOBAL reference atmosphere models
models which have been produced on behalf of NASA to describe the terrestrial atmosphere from
ground level upward for operational purposes
Note 1 to entry: Earth GRAM 2016 is now available as an open-source C++ computer code that can run on a variety
of platforms including PCs and UNIX stations. The software provides a model that offers values for atmospheric
parameters such as density, temperature, winds, and constituents for any month and at any altitude and location
within the Earth's atmosphere. An earlier version, Earth GRAM 2010 is available in FORTRAN.
Note 2 to entry: Earth GRAM 2016 includes the troposphere (3.2), stratosphere (3.3), mesosphere (3.4),
thermosphere (3.5) and exosphere (3.6).
Note 3 to entry: These models now include options for NRLMSIS 2.0, HWM-14 and JB2008.
Note 4 to entry: See https:// software .nasa .gov/ software/ MFS -32780 -2.
Note 5 to entry: It is based on a very large underlying set of supporting data from satellites, rockets, and radars,
with extensive temporal and spatial distribution. It has been extensively tested against experimental data by the
international scientific community. The model has a flexible mathematical formulation.
Note 6 to entry: It is valid for use from ground level to the exosphere (3.6). Two indices are used in this model:
F (both the daily solar flux value of the previous day and the 81-day average centred on the input day) and A
10,7 p
(geomagnetic daily value)
Note 7 to entry: See References [3] and [4].
3.9
JB2008
Jacchia-Bowman 2008 model
model that describes the neutral temperature and the total density in Earth’s thermosphere (3.5) and
exosphere (3.6)
Note 1 to entry: See https:// spacewx .com/ jb2008/ .
Note 2 to entry: Its new features lead to a better and more accurate model representation of the mean total
density compared with previous models, including the NRLMSISE-00 and NRLMSIS 2.0.
Note 3 to entry: It is valid for use from an altitude of 120 km to 2 500 km in the exosphere (3.6). Four solar indices
and two geomagnetic activity indices are used in this model: F (both tabular value one day earlier and the 81-
10,7
day average centred on the input time); S (both tabular value one day earlier and the 81-day average centred
10,7
on the input time); M (both tabular value five days earlier and the 81-day average centred on the input time);
10,7
Y (both tabular value five days earlier and the 81-day average centred on the input time); a (3 h tabular
10,7 p
value); and D (1 h value) (a and D are both used as inputs to create a dT temperature change tabular value on
st p st c
the input time).
Note 4 to entry: See References [5] and [6].
3.10
HWM14
horizontal wind model
comprehensive empirical global model of horizontal winds in the atmosphere
Note 1 to entry: Reference values for the a index needed as input for the wind model are given in Annex A.
p
Note 2 to entry: HWM14 does not include a dependence on solar EUV irradiance. Solar cycle effects on
thermospheric winds are generally small during the daytime, but can exceed 20 m/s at night.
Note 3 to entry: HWM14 thermospheric winds at high geomagnetic latitudes during geomagnetically quiet
periods should be treated cautiously.
ISO 14222:2022(E)
Note 4 to entry: See References [7] and [8].
3.11
DTM-2013
drag temperature model 2013
model that describes the neutral temperature and (major and some minor) species densities in the
Earth’s atmosphere between an altitude of 120 km to approximately 1 500 km
Note 1 to entry: DTM-2013 is based on a large database going back to the early ‘70s, but it is mainly constructed
with high-resolution CHAMP and GRACE accelerometer-inferred data and GOCE thruster-inferred densities.
Note 2 to entry: It is valid from an altitude of 120 km to approximately 1 500 km in the exosphere (3.6). Two
indices are used in this model: F solar flux (both daily solar flux of the previous day and the average of the
previous 81-days) and K (3 h value delayed by 3 h and the average of the last 24 h).
p
Note 3 to entry: The DTM model codes (DTM-2009 and DTM-2013) are available for download on the SWAMI
project website (swami-h2020.eu/).
Note 4 to entry: See References [9] and [10].
3.12
reanalysis model
model that provides access to corrected data sets for any location and any time around the world
EXAMPLE ERA5 (3.13) and NCEP/NCAR reanalysis (3.14).
Note 1 to entry: Reanalysis models provide specific data for locations and periods of interest (e.g. inter-
comparison and calibration measurements) and can also be used to provide examples of extrema of atmospheric
conditions, contrasting with the long-term averages represented by the empirical models described in 3.7 to 3.11.
3.13
ERA5
latest ECMWF (European Centre for Medium Range Weather Forecasting) meteorological reanalysis
project
[11]
Note 1 to entry: The first ECMWF reanalysis product, ERA-15 , generated reanalyses for approximately 15
years, from December 1978 to February 1994. The second product, ERA-40 (originally intended as a 40-year
reanalysis) begins in 1957 (the International Geophysical Year) and covers 45 years to 2002. As a precursor to a
revised extended reanalysis product to replace ERA-40, ECMWF released ERA-Interim, which covers the period
from 1979 to present.
[11],[12]
Note 2 to entry: ERA5 is a new reanalysis product which has recently been released by ECMWF as part of
Copernicus Climate Change Services.
Note 3 to entry: This product has higher spatial (horizontal) resolution (31 km) and covers the period from 1979
to present. Extension back to 1950 is now available.
Note 4 to entry: In addition to reanalysing all the old data, now using a consistent system, the reanalyses also
make use of much archived data that was not available to the original analyses. This allows for the correction of
many historical hand-drawn maps, where the estimation of features was common in areas of data sparsity. ERA5
also has the ability to create new maps of parameters at specific atmosphere levels that were not commonly used
until more recent times.
Note 5 to entry: Accessing the data: The ERA5 data can be downloaded for research use from ECMWF's homepage
(see https:// apps .ecmwf .int/ data -catalogues/ era5/ ?class = ea) and the National Center for Atmospheric Research
data archives. Both require registration.
Note 6 to entry: A Python web API can be used to download a subset of parameters for a selected region and time
period.
Note 7 to entry: ERA5 is a reanalysis model (3.12).
ISO 14222:2022(E)
3.14
NCEP/NCAR reanalysis
continually updated globally gridded data set that represents the state of the Earth's atmosphere,
incorporating observations and numerical weather prediction (NWP) model output from 1948 to
present
Note 1 to entry: It is a joint product from the National Center for Environmental Prediction (NCEP) and the
National Center for Atmospheric Research (NCAR).
Note 2 to entry: Accessing the data: The data is available for free download from the NOAA Earth System
[13] [14]-[18]
Research Laboratory and NCEP. It is distributed in Netcdf and GRIB files, for which a number of tools
and libraries exist.
Note 3 to entry: It is available for download through the NCAR CISL Research Data Archive on the NCEP/NCAR
[16]
Reanalysis main data page .
[17] [18]
Note 4 to entry: Since then, NCEP-DOE reanalysis 2 and the NCEP CFS reanalysis have been released.
Note 5 to entry: The former focuses in fixing existing bugs with the NCEP/NCAR reanalysis system – most notably
surface energy and usage of observed precipitation forcing to the land surface, but otherwise uses a similar
[18]
numerical model and data assimilation system. The latter is based on the NCEP Climate Forecast System .
Note 6 to entry: See https:// psl .noaa .gov/ data/ gridded/ data .ncep .reanalysis .html.
Note 7 to entry: NCEP/NCAR reanalysis is a reanalysis model (3.12).
3.15
SET HASDM density database
database which is used for scientific studies through a SQL database with open community access
Note 1 to entry: The information content of the database originated from the highly accurate densities used to
create the NORAD satellite catalogue and produced by the US Air Force through its High Accuracy Satellite Drag
Model (HASDM) system.
Note 2 to entry: The historical database covers the period from January 1, 2000 through December 31, 2019. Data
records exist every 3 h during solar cycles 23 and 24.
Note 3 to entry: The database has a grid size of 10° × 15° (latitude, longitude) with 25 km altitude steps between
175 km to 825 km.
Note 4 to entry: A description of the source of the database, its validation, its information content and its
accessibility are provided by Reference [19].
Note 5 to entry: See https:// spacewx .com/ hasdm/ .
3.16
first principles atmospheric models
models that use the physical inputs in terms of energy and momentum to the formulae describing the
behaviour of the atmosphere and as such describe the self-consistent evolution of the whole atmosphere
responding to external forcing from the Sun, the oceans, the magnetosphere and solar wind
Note 1 to entry: They include interactions, calculated self-consistently, with the Earth’s ionosphere at higher
altitudes (upper mesosphere (3.4), thermosphere (3.5)).
Note 2 to entry: See References [20] to [28].
ISO 14222:2022(E)
3.17
WAM
whole atmosphere model
model developed in collaboration with the NOAA Space Weather Prediction and Environmental
Modeling Centers (SWPC and EMC) by vertical extension of the operational Global Forecast System
(GFS) model over the last decade
Note 1 to entry: The model has demonstrated remarkable performance in simulating climatology and daily
variability of the upper atmosphere and ionosphere driven from below. Coupled to ionosphere-electrodynamics
models, it not only reproduced dramatic variations of ionospheric plasma drifts and density distribution
observed during sudden stratospheric warmings but also demonstrated predictive capability with lead times
up to 2 weeks. WAM has reached a level of maturity to be implemented into operations at the National Weather
Service (NWS).
Note 2 to entry: Within the same timeframe NWS also plans to substantially upgrade GFS to the Next Generation
Global Prediction System (NGGPS). Specific capabilities of NGGPS include in particular a nonhydrostatic
dynamical core and the ability to directly simulate important processes such as tropospheric convection at very
high resolution globally and without the need for parameterization. This opens an opportunity for development
of the Next Generation WAM (NGWAM). Specific requirements for extension of NGGPS into NGWAM will be
discussed and capabilities of the new models in application to the upper atmosphere and ionosphere dynamics,
simulation and prediction presented.
Note 3 to entry: See References [20]to [23].
3.18
CTIPe
coupled thermosphere ionosphere plasmasphere electrodynamics model
model that consists of four distinct components: a global thermosphere (3.5) model; a high-latitude
ionosphere model; a mid and low-latitude ionosphere/plasmasphere model; an electrodynamical
calculation of the global dynamo electric field, with all four components running concurrently and fully
coupled with respect to energy, momentum and continuity
Note 1 to entry: See References [24] to [28].
4  Symbols and abbreviated terms
a the 3 h planetary geomagnetic index given in nT
p
A the daily planetary geomagnetic index given in nT
p
CIRA COSPAR international reference atmosphere
COSPAR Committee on Space Research
D the hourly disturbance storm time ring current index given in nT
st
−22 −2
F the F solar proxy given in units of solar flux, ×10 W m
10 10,7
F the solar energy proxy that is used in the DTM-2013; it corresponds to the solar radio flux
emitted by the Sun at 1,000 megaHertz (30 cm wavelength)
−22 −2
M the M solar proxy given in units of solar flux, ×10 W m
10 10,7
−22 −2
S the S solar index given in units of solar flux, ×10 W m
10 10,7
SET Space Environment Technologies
URSI International Union of Radio Science
−22 −2
Y the Y solar index given in units of solar flux, ×10 W m
10 10,7
ISO 14222:2022(E)
5  General concept and assumptions
5.1  Earth's atmosphere model use
5.1.1 General
NOTE 1 ISO/TR 11225 provides an extensive listing of many empirical and first principles atmospheric models
used since before the beginning of the space age up through the modern era.
[1],[2]
The NRLMSIS 2.0 should be used for calculating both the neutral temperature and the detailed
composition of the atmosphere from ground level upward.
[3],[4]
The Earth GRAM 2016 should be used for calculating the total atmospheric density from ground
level upward.
[5],[6]
The JB2008 model should be used for calculating the total atmospheric density from 120 km to the
exosphere.
[7],[8]
The HWM14 should be used for horizontal winds from ground level upward.
[9],[10]
The DTM-2013 should be used for calculating the total atmospheric density above an altitude of
120 km, for example as used in determining satellite drag in low Earth orbit.
[1],[2] [3],[4] [11],[12]
For altitudes below 120 km, NRLMSIS 2.0 , Earth-GRAM 2016 , ECMWF ERA5 , NCEP/
[13]-[18] [20]-[23]
NCAR reanalysis or WAM should be used for calculating the total air density.
[19]
The SET HASDM density database should be used as a baseline reference for solar cycles 23 and 24
thermospheric densities with a time cadence of 3 h, an altitude range of 175 km to 825 km in 25 km
steps and a latitude/longitude bin size of 10° × 15°.
[20]-[23]
WAM should be used primarily for scientific analysis of specific events, from ground level
upward.
[24]-[28]
CTIPe should be used for investigations of atmospheric and Ionospheric parameters above
approximately 100 km, when the response to specific solar and geomagnetic conditions and events is
under investigation.
NOTE 2 This usage follows the advice of the CIRA Working Group, sponsored by COSPAR and URSI, following
the resolution of the COSPAR Assembly in Montreal in July 2008.
5.1.2 Application guidance
a) The NRLMSIS 2.0 model for species densities should not be mixed with the JB2008, Earth
GRAM 2016 or DTM-2013 for total density.
b) For worst-case high solar activity results and analysis periods not exceeding 1 week, high daily
short-term values given in Annex A should be used as input for daily activity together with the high
long-term values for the 81-day average activity.
c) For analysis periods longer than 1 week the long-term solar activity activities given in Annex A
should be used as input for both the daily and the 81-day averaged values.
d) For analysis periods longer than 1 week and conditions specified in Annex A, the daily and 81-day
averaged solar activities given in Annex A should be used.
e) Short-term daily high solar activity values should not be used together with low or moderate long-
term solar activity values.
NOTE 1 The NRLMSIS 2.0, Earth GRAM 2016, JB2008, and DTM-2013 can only predict large scale and slow
variations, on the order of 1 000 km (given by the highest harmonic component) and 3 h.
ISO 14222:2022(E)
Spacecraft can often encounter density variations with smaller temporal and spatial scales. This is
partly since the spacecraft are in motion (for example, +100 % or −50 % in 30 s) and partly because
smaller-scale disturbances certainly do occur during periods of disturbed geomagnetic activity.
NOTE 2 Reference values for the key indices needed as inputs for the atmosphere models are given in Annex A.
NOTE 3 The F 81-day average solar activity can also be estimated by averaging three successive monthly
10,7
predicted values.
NOTE 4 Information on density model uncertainties can be found in Annex A and in References [1] to [4].
NOTE 5 For high solar activities, the atmosphere models only give realistic results if high short-term values
are combined with high 81-day averaged values.
NOTE 6 High D values can be used corresponding to low, moderate or high solar activities.
st
5.2  Earth wind model use
[7],[8]
The HWM14 should be used from ground level upward.
High daily short-term solar activity values should be used as worst-case for the daily activity but the
81-day average activity should not exceed the high long-term value.
NOTE 1 Reference values for the key indices needed as inputs for the wind model are given in Annex A.
NOTE 2 The F 81-day average solar activity can also be estimated by averaging three successive monthly
10,7
predicted values as given in Annex A.
NOTE 3 The use of the HWM14 model at high geomagnetic latitudes and for disturbed geomagnetic periods
necessitates caution in the interpretation of model results.
5.3  Robustness of standard
The Earth’s atmosphere models described in this document are intended to be adapted and improved
over time as the international scientific community obtains and assesses high quality data on the
atmosphere. Therefore, the users of the models described should ensure they utilize the latest version
of the respective models.
There are subtle differences between the recommended models.
These reflect differences between the selection of the very many data sources used in these models,
although these generally overlap or may even be identical in many cases. However, the weighting
applied to the individual data sets may differ. The mathematical formulation of the various empirical
models is also distinct.
Differences between the model’s predictions for specific location and conditions are generally small
compared with the variability of the atmosphere. Users may find that one specific model is more
convenient for their specific application than another. Users should, however, be very careful not to mix
and merge atmospheric parameters from one model with those from another distinct model.
5.4  Long-term changes of the atmosphere
As the result of increasing levels of CO and CH in the Earth’s atmosphere, the mean temperature of the
2 4
troposphere and stratosphere have warmed, due to the increased thermal blanketing effect. At higher
levels – the mesopause and lower thermosphere, the thermal effect is reversed since increased mixing
ratios of these thermally-active gases are free to radiate to cold space. The result is a cooling of the
upper mesosphere and lower thermosphere and the consequent changes in the thermal and density
[29]
structure of the middle and upper thermosphere. These effects are highlighted in Figure 1 .
ISO 14222:2022(E)
Key
X year
Y dT (K)
c
1 formula
a
Change in 81-day exospheric temperature, dT , at 400 km for F10B = 68-73.
c
b
Slope = −3,7 degree per decade + −0,1.
= −3,1 % density per decade.
Figure 1 — Changes in temperature at solar minimum at 400 km altitude over 4 solar cycles
These changes of the temperature atmosphere (and consequently density) of the thermosphere are
under detailed scrutiny. There are the significant effects on orbital drag (decreased) and the lifetime
of artificial satellites and orbital debris (increased). The embedded ionosphere is also affected (for
example a reduction in the height of f F (height of the maximum of the F region). It is intended that
o 2 2
these effects should be analysed in detail and presented in a systematic way in a future revision of this
document.
ISO 14222:2022(E)
Annex A
(informative)
Neutral atmospheres
A.1 Structure of the Earth’s atmosphere
The Earth’s atmosphere can be classified into different regions based on temperature, composition,
or collision rates among atoms and molecules. For the purposes of the document, the atmosphere is
broadly divided into three regimes based on all three properties, as shown in Figure A.1:
a) The homosphere (3.1, 3.2, 3.3, 3.4);
b) The thermosphere (3.5);
c) the exosphere (3.6);
In practice, the boundaries between these regions, whether determined in altitude or in a pressure co-
ordinate system, vary with solar, seasonal, latitudinal and other conditions.
Due to winds and turbulent mixing the homosphere has a nearly uniform composition of about 78,1 %
N , 20,9 % O and 0,9 % Ar. The temperature profile of the thermosphere increases rapidly above a
2 2
minimum of ~180 K at the mesopause, then gradually relaxes above ~200 km to an asymptotic value
known as the exospheric temperature.
ISO 14222:2022(E)
Key
X temperature (Celsius)
Y altitude
1 troposphere
2 stratosphere
3 mesosphere
4 thermosphere
5 exosphere
Figure A.1 — Temperature profile of the Earth’s atmosphere
ISO 14222:2022(E)
A.2 Development of models of the Earth’s atmosphere
A “standard atmosphere” is defined as a vertical distribution of atmospheric temperature, pressure
and density, which by international agreement is taken to be representative of the Earth’s atmosphere.
The first “standard atmospheres” established by international agreement were developed in the 1920’s
primarily for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft
and rocket design, ballistic tables, etc. Later some countries, notably the United States, also developed
and published “standard atmospheres”. The term “reference atmosphere” is used to identify vertical
descriptions of the atmosphere for specific geographical locations or globally. These were developed
by organizations for specific applications, especially as the aerospace industry began to mature after
World War II. The term “standard atmosphere” has in recent years also been used by national and
international organizations to describe vertical descriptions of atmospheric trace constituents, the
ionosphere, atomic oxygen, aerosols, ozone, winds, water vapour, planetary atmospheres, etc.
[30]
Currently some of the most commonly used standard and reference atmospheres include: the ISO
standard atmosphere 1975, 1982; the U.S. standard atmosphere supplements, 1962, 1966, 1976; the
COSPAR international reference atmosphere (CIRA) 1986 (previously issued as CIRA 1961, CIRA 1965
and CIRA 1972); the NASA/MSFC global reference atmosphere model, Earth GRAM 2007 (previously
issued as GRAM-86, GRAM-88, GRAM-90, GRAM-95 and GRAM-99); the NRLMSISE-00 thermospheric
model 2000 (previously issued as MSIS-77, −83, −86 and MSISE-90); and most recently the JB2006 and
JB2008 density models.
A.3 NRLMSIS 2.0 and JB2008 - Additional information
The mass spectrometer and incoherent scatter (MSIS) series of models developed between 1977
and 1990 are used extensively by the scientific community for their superior description of neutral
composition. The models utilized atmospheric composition and temperature data from instrumented
satellites and ground-based radars. The initial MSIS 1977 model utilized a Bates-Walker temperature
profile (which is analytically integrable to obtain density) and allowed the density at 120 km to vary
with local time and other geophysical parameters to fit the measurements. The temperature and
density parameters describing the vertical profile were expanded in terms of spherical harmonics to
represent geographic variations. Subsequent versions of the model include the longitude variations, a
refined geomagnetic storm effect, improved high latitude, high solar flux data and an extension of the
lower boundary down to sea level.
The NRLMSIS 2.0 model represents atmospheric composition, temperature and total mass density from
the ground to the exosphere. Its formulation imposes a physical constraint of hydrostatic equilibrium
to produce self-consistent estimates of temperature and density. NRLMSIS 2.0 includes the following
enhancements compared to MSISE-90:
a) drag data based on orbit determination;
b) more recent accelerometer data sets;
c) new temperature data derived from Millstone Hill and Arecibo incoherent scatter radar
observations;
d) observations of O by the solar maximum mission (SMM), based on solar ultraviolet occultation;
+
e) a new species, “anomalous oxygen”, primarily for drag estimation, allows for appreciable O and
hot atomic oxygen contributions to the total mass density at high altitudes.
The Jacchia-Bowman density model (JB2008) is based on the Jacchia model heritage. It includes two
key novel features. Firstly, there is a new formulation concerning the semi-annual density variation
observed in the thermosphere, but not previously included in any of the semi-empirical atmospheric
models. Secondly, there is a new formulation of solar indices, relating more realistically the dependence
of heat and energy inputs from the solar radiation to specific altitude regions and heating processes
within the upper atmosphere. The D index (equatorial magnetic perturbation) is used in JB2008 as the
st
index representing the geomagnetic activity response. JB2008 inserts the improved J70 temperature
ISO 14222:2022(E)
formulations into the CIRA 1972 model to permit integrating the diffusion equation at every point rather
than relying on look-up tables (the integration must be done numerically, in contrast to the analytically
integrable Bates-Walker temperature formulation used in MSIS). In order to optimally represent the
orbit-derived mass density data on which JB2008 is based, the model formulation sacrifices the physical
constraint of hydrostatic equilibrium since it does not include all physical processes that may actually
be present in thermosphere affecting temperatures and densities.
A.4 The series of atmosphere models
The National Aeronautics and Space Administration’s NASA/MSFC global reference atmospheric model
version 2007 (Earth GRAM 2007) is a product of the Natural Environments Branch, NASA Marshall
Space Flight Center. These models are available via license to qualified users and provide usability and
information quality similar to that of the NRLMSISE-00 model. Like the previous versions of GRAM,
the model provides estimates of means and standard deviations for atmospheric parameters such
as density, temperature and winds, for any month, at any altitude and location within the Earth’s
atmosphere. GRAM can also provide profiles of statistically-realistic variations (i.e. with Dryden energy
spectral density) for any of these parameters along computed or specified trajectory. This perturbation
feature makes GRAM especially useful for Monte-Carlo dispersion analyses of guidance and control
systems, thermal protection systems and similar applications. GRAM has found many uses, both inside
and outside the NASA community. Most of these applications rely on GRAM’s perturbation modelling
capability for Monte-Carlo dispersion analyses. Some of these applications have included operational
support for shuttle entry, flight simulation software for X-33 and other vehicles, entry trajectory and
landing dispersion analyses for the Stardust and Genesis missions, planning for aerocapture and
aerobraking for Earth-return from lunar and Mars missions, six-degree-of-freedom entry dispersion
analysis for the multiple experiment transporter to Earth orbit and return (METEOR) system and more
recently the crew exploration vehicle (CEV). Earth GRAM 2007 retains the capability of the previous
version but also contains several new features. The thermosphere has been updated with the new
Air Force JB2008 model, while the user still has the option to select the NASA Marshall engineering
thermosphere (MET) model or the Naval Research Laboratory (NRL) mass spectrometer, incoherent
scatter (M
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